Micromechanical actuators are known as having a membrane structure, which is produced with the technology of semiconductor materials. The membrane, provided with one or more piezoelectric elements, is made to deflect in a driving direction by appropriate control of the piezoelectric elements. The mechanical deformation of the membrane has a specific utility according to the application in which it is used. For instance, in fluidic applications, the membrane may form part of a micropump or a printhead, and its deflection may be used to cause displacement of a mass of fluid.
Other applications of micromechanical actuators include, for example, acoustic applications. Piezoeletrically actuated membranes are, for example, used in miniaturized speakers that are integrated in portable apparatuses, such as portable computers, laptops, notebooks (including the ultra-thin notebooks), PDAs, tablets, and smartphones.
Thanks to the small dimensions, said devices make it possible to respect stringent requirements regarding the occupation of space, in terms of both area and thickness.
It has been found that, frequently, the deflection required of membranes of actuators of a known type is of several hundreds of micrometers (500-2000 μm) in a direction orthogonal to the plane of the membrane itself (out-of-plane deflection). This performance may be obtained by increasing the area of the membrane, at the expense of occupation of space.
There is a need in the art to provide a micro-electro-mechanical device with piezoelectric actuation that will overcome the drawbacks of the prior art.